Use cases for the where filter in Shopify Liquid

where-filter.liquid

{% # Checking the presence of a block %}
{% liquid
  assign announcement_block_list = section.blocks | where: 'type', 'announcement'
  if announcement_block_list == empty
    # Take action to prepare fallback content
  endif
%}

/////////////////////////////////////////

{% # Limitless metaobject retrieval from handle %}
{% liquid
  assign metaobject_value_list = shop.metaobjects.color.values
  assign target_handle = 'yellow'
  
  assign target_system = metaobject_value_list | map: 'system' | where: 'handle', targer_handle | first
  if target_system
    assign target_metaobject = metaobject_value_list | where: 'system', target_system
  endif
  
  # Now, the 'target_metaobject' variable contains the MetaobjectDrop corresponding to the Yellow color
  # Note that if you have more than 50 entries, the target entry may not be part of 'metaobject_value_list'
%}

/////////////////////////////////////////

{% # Get product variants corresponding to customer group %}
{% liquid
  assign visitor_translation = 'user_group.visitor' | t
  assign vip_translation = 'user_group.vip' | t
  
  assign user_group = customer.metafields.user.group.value | default: visitor_translation
  if user_group == vip_translation
    assign product_variant_list = product.variants | where: 'option1', vip_translation
  else
    assign product_variant_list = product.variants | where: 'option1', visitor_translation
  endif
  
  # This logic will render correct data for both VIP customers as well as visitors
%}

/////////////////////////////////////////

{% # Sort metaobject entries by creation date %}
{% liquid
  # You need to setup a "date" field inside the metaobject
  assign metaobject_value_list = shop.metaobjects.color.values
  
  assign date_list = metaobject_value_list | map: 'date' | compact | sort_natural

  for date in date_list
    assign associatedEntry = metaobject_value_list | where: 'date', date
    assign sorted_value_list = sorted_value_list | concat: associatedEntry | uniq
  endfor

  # 'sorted_value_list' is now ordered according to the date
  # Note that if you have more than 50 entries, the sorting may be incomplete as some entries are ommited
%}

/////////////////////////////////////////

{% # Recreating the specialized cart filters with existing ones %}
{% liquid
  assign newVariantInCartQuantity = cart | item_count_for_variant: variantId
  assign oldVariantInCartQuantity = cart.items | where: 'variant_id', variantId | map: 'quantity' | sum

  assign newProductInCartList = cart | line_items_for: targetProduct
  assign oldProductInCartList = cart.items | where: 'product_id', productId

  assign newVariantInCartList = cart | line_items_for: targetVariant
  assign oldVariantInCartList = cart.items | where: 'variant_id', variantId
%}